In recent years, the MIMO antenna system has come under attention as a transmission technology for wireless communications. This MIMO antenna system provides a plurality of transmitting/receiving antennas at a transmitting side of a wireless communication system and provides a plurality of transmitting/receiving antennas at that receiving side and has these multi-antennas transmit and receive information. In this MIMO antenna system, a large number of communication paths are formed between all antennas of the transmitting side and all antennas of the receiving side. As a result, the speed of data transmitted from the transmitting side to the receiving side is multiplied. For example, if using two transmitting antennas, the speed of that transmitted data is doubled, while if using four, it is quadrupled. Therefore, the channel capacity between the transmitter and receiver can be greatly increased. However, in this case, it is assumed that the bit correlation between the plurality of transmitting antennas is sufficiently small and the bit correlation between the plurality of receiving antennas is sufficiently small.
On the other hand, further, in recent years, a LDPC (Low Density Parity Check) code has begun to be used for encoding the transmitted data in a wireless communication system etc. This LDPC code, like the conventional turbo code, is an error correction code having superior characteristics close to the Shannon limit.
In particular, it is known that this LDPC code has a decoding characteristic equal to the turbo code or, when that code length is long, exhibits better characteristics than the turbo code. For example, when the code length is tens of thousands of bits or more, sometimes it exceeds the decoding characteristic of the turbo code currently employed in third generation mobile phone systems.
As the LDPC code, currently a binary type LDPC code and a non-binary type LDPC code are known, but if the latter non-binary LDPC code is used, there is the defect that the amount of processing increases compared with the former binary LDPC code. However, while there is such a defect, if this non-binary LDPC code is used, even if the code length becomes short, an improvement of the decoding characteristic can be expected compared with use of the binary LDPC code.
Therefore, it can be easily understood that by using both the MIMO antenna system and non-binary LDPC coding system, a wireless communication system can be realized which increases the channel capacity between the transmitter and receiver and further simultaneously improves the decoding characteristic.
When realizing a high efficiency wireless communication system using this MIMO antenna system and non-binary LDPC coding system, first, it is proposed, based on the general technique of constructing current wireless communication systems using the general binary LDPC coding system for that MIMO antenna system, to construct a high efficiency wireless communication system using the intended non-binary LDPC coding system of the present invention together with that MIMO antenna system.
That is, a new technique utilizing the normal technique of using both a MIMO antenna system and general binary LDPC coding system realizes the high efficiency wireless communication system using both a MIMO antenna system and non-binary LDPC coding system.
However, if trying to use the normal technique as it is to realize the high efficiency wireless communication system using both the non-binary LDPC coding system and MIMO antenna system, due to the later explained reasons, the problem arises of both the information regarding the bit correlation between the plurality of transmitting antennas in the MIMO antenna system and information regarding the inter-bit correlation in the modulated symbols being lost (loss of correlation information) and of the decoding characteristic of the non-binary LDPC code at the receiving side ending up deteriorating.
This being so, as already explained, the advantage of improvement of the decoding characteristic expected when using a non-binary LDPC code ends up being cancelled out by the disadvantage of the deterioration of the decoding characteristic due to the loss of correlation information. As a result, the advantage of using the non-binary LDPC code is lost and therefore realization of an effective high efficiency wireless communication system becomes difficult.
Note that as known in prior art relating to the present invention, there are the following [Non-Patent Document 1] and [Non-Patent Document 2].    [Non-Patent Document 1] M. C. Davey and D. MacKay, “Low-Density Parity Check Codes over GF (q)”, IEEE Comm. Lett., Vol. 2, No. 6, June 1998.    [Non-Patent Document 2] F. Guo and L. Hanzo, “Low complexity non-binary LDPC and modulation schemes over MIMO channels”, Vehicular Technology Conference, 2004, VTC2004-Fall, vol. 2, pp. 1294-1298, September 2004.